KR20000071637A - Nickel-free white copper alloy - Google Patents

Abstract

A nickel-free white copper alloy represented by the following chemical formula and containing incidentally unavoidable elements.

Chemical formula

Cu _a Zn _b Mn _c Al _d

Chemical formula

Cu _a Zn _b Mn _c Al _d X _e

In the above formula,

X is at least one element selected from the group consisting of Si, Ti and Cr,

b, c, d and e are weight percent, 0.5≤b <5, 7≤c≤17, 0.5≤d≤4 and 0 <e≤0.3,

a is the remainder

The alloy is free from allergic problems that can be caused by nickel and has excellent strength, hardness, ductility, processability and corrosion resistance suitable for use in elements such as slide fasteners, sliders, stoppers, etc., or garment metal buttons, fasteners and the like. .

Description

Nickel-free white copper alloy {NICKEL-FREE WHITE COPPER ALLOY}

Background of the Invention

1. Field of Invention

The present invention is excellent in strength, hardness, ductility, workability and corrosion resistance, suitable for use in accessories such as slider fasteners, sliders, stoppers, or metal buttons for clothing, fasteners, etc., and does not cause allergy problems and has a high whiteness. -Nickel nickel alloys.

2. Description of the prior art

For example, the above-mentioned conventional copper alloys for fasteners include copper-nickel-zinc alloys having a white alloy color, such as nickel silver, or copper-zinc represented by red brass or brass. Alloys have been used. Since nickel silver contains nickel as an alloying element, it is excellent in corrosion resistance. However, for example, when using it as a slide fastener, the fastener often comes into contact with the skin and allergic problems due to nickel arise. On the other hand, copper-zinc alloys represented by red brass or brass do not contain nickel and thus do not cause this allergy problem. However, its hue becomes yellowish, and a white alloy cannot be obtained.

Summary of the Invention

Accordingly, it is an object of the present invention to provide a copper alloy having excellent workability, corrosion resistance and whiteness, together with excellent strength and hardness, and ductility equivalent to that of nickel silver, and free from allergic problems because the alloy does not contain nickel.

The present invention includes the following (1) to (5).

(1) A nickel-free white copper alloy represented by the following chemical formula and containing incidentally unavoidable elements.

Chemical formula

Cu _a Zn _b Mn _c Al _d

In the above formula,

b, c and d are by weight, 0.5 ≦ b <5, 7 ≦ c ≦ 17 and 0.5 ≦ d ≦ 4,

a is the remainder

(2) A nickel-free white copper alloy represented by the following chemical formula and containing incidentally unavoidable elements.

Chemical formula

Cu _a Zn _b Mn _c Al _d X _e

In the above formula,

X is at least one element selected from the group consisting of Si, Ti and Cr,

b, c, d and e are in weight percent, 0.5 ≦ b <5, 7 ≦ c ≦ 17, 0.5 ≦ d ≦ 4 and 0 <e ≦ 0.3,

a is the remainder

(3) The nickel-free white copper alloy described in (1) or (2) above, wherein b, c and d are by weight%, 0.5 ≦ b ≦ 4, 7 ≦ c ≦ 15 and 0.5 ≦ d ≦ 2.

(4) The nickel-free white copper alloy described in any one of (1), (2) and (3) above, wherein the alloy is in a single α-phase state at room temperature.

(5) Said (1), (2), and which the alloy has the color tone which a * value and b * value which show the color tone prescribed | regulated by JIS Z 8729 are 0 <a * <5 and 7 <b * <15. Nickel-free nickel alloy as described in (3).

Detailed Description of the Preferred Embodiments

In the composition of the present invention, Zn has the effect of improving the mechanical properties of the alloy through its solid solution reinforcing effect and also the price reduction effect of the alloy. If the Zn content is 0.5% or less, the cost reduction effect and the strengthening effect are insufficient. If the content is 5% or more, the solid-solution coexistence temperature range becomes wider and the macroscopic separation tends to be remarkable. In addition, thermal conductivity and castability tend to be reduced. Moreover, when the Zn content is 5% or more, the season cracking resistance is lowered and the crystal structure becomes alpha + beta phase, so that sufficient cold workability cannot be secured. By fixing at 5% or less, no aging cracking problem occurs and even more stable state can be maintained even when the X element defined in the above-mentioned formula Cu _a Zn _b Mn _c Al _d X _e is added. Mn is effective in providing improved mechanical properties to the alloy by the solid solution strengthening effect and also in reducing the price of the alloy. Moreover, by adding Mn in the above-mentioned amount as a partial replacement of zinc, the effect of improving aging crack resistance and the effect of preventing excessive yellowing of the copper alloy color tone are produced. In addition, there is an effect of lowering the melting point of the alloy, thereby improving castability and suppressing evaporation of zinc from the melt. At 7% or less, the hue is yellowish. In contrast, when 17% or more, the crystal structure becomes alpha + beta phase, sufficient cold workability cannot be secured. The upper limit of Mn is more preferably 15%.

Al has the effect of improving the aging crack resistance by forming a stable oxide film on the alloy surface. In addition, Al improves the mechanical properties of the alloy through the solid solution strengthening effect and reduces the price of the alloy. The lower limit of Al is 0.5%. If the amount is too small, the aging crack resistance and the strengthening effect are insufficient. On the other hand, if it is 4% or more, the crystal structure becomes alpha + beta phase and sufficient cold workability cannot be secured. 2% or less is more preferable.

In the formula Cu _a Zn _b Mn _c Al _d X _e , the X element (at least one element selected from the group consisting of Si, Ti and Cr) acts as an encapsulation on the surface of the melt during melting, as well as oxidation of Zn and Zn It also serves to prevent evaporation. Furthermore, by forming a stable oxide film on the surface of the alloy, the effect of preventing the removal of Mn and the aging crack resistance during annealing, and also the effect of preventing the change of color tone over time due to the oxidation of Mn. The lower limit of the amount of X elements is 0% or more. However, if the amount is too small, the above effect is not sufficiently obtained. Therefore, the amount is preferably 0.02% or more. If the amount is 0.3% or more, an element and an intermetallic compound in the composition are formed, resulting in a decrease in cold workability.

The alloy of the present invention is composed of a single α phase and can secure sufficient cold workability. If it is outside the composition range of this invention, a crystal structure will become the (alpha) + (beta) phase easily, and workability will fall.

In addition, the alloy of the present invention is in the range of 0 <a * <5 and 7 <b * <15 based on the chromaticity diagram of the (L * a * b *) colorimetric system when prescribed by JIS Z 8729.

The color tones referred to herein are the psychometric brightness index L * (brightness: L star) and the psychometric chromaticity index a * (green-red: a star) expressed according to the specification table of the material color specified by JIS Z 8729 and b * (blue-yellow: b star). In particular, in order to be white, which is a feature of the present invention, it is better to be colorless, and can be defined by the chromaticity indices a * and b * as described above.

The present invention will be specifically described based on the following examples.

Example

In Examples 1 to 14 of the present invention shown in Table 1, test materials were prepared and evaluated as described below. The same procedure is followed for Comparative Examples 1-10 of Table 1.

Pure Cu (99.9%), Pure Zn (99.9-99.99%), Pure Mn (99.9%), Pure Al (99.99%), Pure Ti, Pure Si and Pure Cr for 200 cm ³ each ingot Measure for configuration. Each composition is high frequency melted in an Ar atmosphere (10 cm Hg), held for 4 minutes and then poured into a copper mold (40 mm diameter x 28 mm length). The obtained ingot (200 cm ³ ) is cut to about 70 mm length to form a billet for extrusion. Extrusion is carried out at a billet temperature of 800 ° C. and a container temperature of 600 ° C. The obtained extrudate (diameter 8 mm x about 1300 mm in length) was heated at 800 ° C. for 1 hour and then cooled in a furnace (hereinafter referred to as “heat treatment”). An extrudate (wire) to which this heat treatment is applied is used as a test substrate.

The obtained test material was mirror polished with SiC abrasive paper and diamond paste, and then measured using a chromatic colorimeter (CR-300, manufactured by Minolta Ltd.), and the results were determined as L *, a * as specified in JIS Z 8729. And b *.

All test materials of the present invention have a white tint, and when used as fastener parts, parts which give a high-quality feel can be provided.

In addition, each of the test materials thus prepared is observed for the microcrystalline structure. The test materials of the present invention were all single α-phase alloys and can provide a material having good cold workability. When the second phase coexisted as in the comparative example, cracks or the like occurred during cold work. No cracking or the like was observed in the materials of the inventive examples. In particular, when used as an element of a fastener, a Y-shaped element fits into a cloth and is attached. The fastener element made of the material of the present invention can be firmly attached to the cloth without cracking or the like.

Hardness (Hv) is represented by the value DPN measured with a Vickers microhardness tester under 25 g load. It is understood that the material of the present embodiment has a hardness equal to or greater than that of the nickel silver (Comparative Example 10) currently used as the fastener part, and has mechanical properties such as strength or hardness that are suitable for the fastener part.

In addition, by cold compression test, 80% strain is given to the obtained test material and the presence of cracks on the surface is observed.

In Table 1, "O" indicates that no crack was present on the material surface, and "X" indicates that crack was present on the material surface. In all of the materials of the inventive examples, it is understood that no cracks were present on the surface. Although used in the case of fastener elements, up to 80% strain is given in cold when the element is attached to the cloth as described above, but the material of the embodiment of the present invention has no problem even when given 80% strain in cold. None is understood.

The resulting test material was mirror polished with SiC abrasive paper and diamond paste, and then tested for discoloration resistance by performing constant temperature and humidity tests by exposing it to 80 ° C. and 90% RH atmosphere. The surface of the test material is then evaluated using a colorimetric colorimeter. The evaluation of discoloration resistance is carried out based on the numerical value obtained by substituting the index before and after the constant temperature and humidity test in the following formula.

Discoloration =

(Wherein a *, b * and L * are indices before the constant temperature and humidity test, and a '*, b' * and L '* are indices after the constant temperature and humidity test)

From the test results, it can be clearly seen that the material of the embodiment of the present invention gives a small value in the above-described formula and has excellent discoloration resistance. From this fact, it is understood that when the material of the present invention is used as a fastener part, such fastener part shows high discoloration resistance to hot wash. In this test, hot water washing in Europe is performed as standard.

The aging crack resistance is evaluated as follows. 80% stress was applied to the test material by cold compression test, the test material was exposed to ammonia using an aqueous 12.5% ammonia solution, and then crack formation was observed on the surface. In Table 1, "O" indicates that no crack was present on the material surface, and "X" indicates that crack was present on the material surface. In all the materials of the inventive examples, it is understood that no cracks were present on the surface. From this fact, it is understood that the present invention can provide a material that is free from problems such as cracking due to the applied strain even when it is fitted into the cloth as a fastener element.

The present invention provides a nickel-free copper alloy having excellent workability and corrosion resistance, together with excellent strength and hardness, and ductility equivalent to that of nickel silver. Even when used as an element for fasteners, sliders, stoppers, etc., or accessories such as buttons, stoppers for garments, and articles that come into contact with the skin, it does not contain nickel, so there is no fear of an allergic reaction to such articles and a beautiful white color. This is maintained, the decorative value is also high.

Claims (5)

A nickel-free white copper alloy represented by the following chemical formula and containing incidentally unavoidable elements. Chemical formula Cu _a Zn _b Mn _c Al _d In the above formula, b, c and d are by weight, 0.5 ≦ b <5, 7 ≦ c ≦ 17 and 0.5 ≦ d ≦ 4, a is the remainder A nickel-free white copper alloy represented by the following chemical formula and containing incidentally unavoidable elements. Chemical formula Cu _a Zn _b Mn _c Al _d X _e In the above formula, X is at least one element selected from the group consisting of Si, Ti and Cr, b, c, d and e are weight percent, 0.5≤b <5, 7≤c≤17, 0.5≤d≤4 and 0 <e≤0.3, a is the remainder The nickel-free white copper alloy according to claim 1 or 2, wherein b, c and d are in weight percent of 0.5 ≦ b ≦ 4, 7 ≦ c ≦ 15 and 0.5 ≦ d ≦ 2. The nickel-free white copper alloy according to any one of claims 1 to 3, wherein the alloy is in a single α-phase state at room temperature. The alloy according to any one of claims 1 to 3, wherein the alloy has a color tone in which the a * and b * values representing the color tone defined by JIS Z 8729 are 0 <a * <5 and 7 <b * <15. Is nickel-free nickel alloy.